Current machines which allow a rowing movement are of two types in which the user is either seated or sanding. With seated machines the user either sits on the floor, or a seat and pulls on a bar attached to the end of a cable which is passed beneath one pulley and over the top of a second pulley attached to a weight. The second pulley is positioned above the first such that when the cable is pulled the weight is lifted towards the second pulley, providing resistance to the pulling movement. A further type of machine used in a seated rowing movement uses a pivot with an two arms attached to it at approximately 90 degrees to each other. One arm is approximately vertical, with a bar or handle fixed on its end for the user to hold, and is pulled on by the user and the second arm is approximately horizontal with weights attached to its end. When the first arm is pulled on it rotates about the pivot and rotates the second arm about the pivot, lifting the weight, and providing resistance to the pulling movement.
A machine which is used with the user standing comprises an arm, one end of which is pivotally fixed to the floor with weights placed on the other end. A handle is fixed towards the weighted end of the arm. The user stands astride the arm and grasps the handle and whilst bent over, lifts the weight towards his chest in a rowing action.
Machines which allow a pull up movement comprise a cable, one end of which is pulled on by the user and extends vertically above the user to a pulley. The cable is tuned around this pulley until it is horizontal and then around a further pulley until it is vertical and its end attached to a weight. The user pulls down on the cable and the cable turns around the two pulleys and lifts the weight to provide resistance. Pivot type machines are also used for pull up type vertical movements.
Machines have also been used which allow horizontal and vertical movements to be carried out on the same machine. These usually comprise a combination of the two types of machine which use cables. Here the cable from the vertical movement is extended and passed around a pulley close to the floor. The user sits on the floor and pulls on the end of this cable.
Machines which are used to exercise the chest with the user in a seated position often use a approximately vertical arm attached to a pivot with a further arm attached to the pivot onto the end of which weights are placed. A handle is placed on the end of the first arm and the user pushes on the handle which rotates both arms about the pivot and lifts the weight. The pivot can be above the head of the user or close to the floor. The resistance can also be provided by a system of pulleys lifting a weight stack. With this type of machine the exercise movement is along a circular arc about the pivot, some machines also use a track which runs parallel to the direction of movement of the exercise giving a linear movement.
The shoulder muscles are also exercised on similar machines with pivots or parallel tracks. When the shoulder muscles are exercised in a seated position, the pivot is usually positioned at a point just above the shoulder joint of the user with the arm which the user holds approximately horizontal.
The limitations of current machines for exercising the back muscles are that when vertical and horizontal movements are combined on the same machine, saving the number of machines and the amount of weight required, then additional pulleys increase friction on the movement and reduce the effectiveness of the movement, particularly when the weight is lowered, because friction helps to lower the force needed to control the lowering of the weight. The machines also use different body positions for the user for example sitting on a seat for one movement and the floor for another, making the machine uncomfortable and inconvenient to use.
Some machines also allow the muscles of the back, chest and shoulders to be exercised on the same machine. These use different methods to exercise each muscle group for example the chest is often exercised on a pivoted arm, and the vertical pull downs form the back performed with a cable passing over a pulley and lifting a weight. The position of the body of the user may also be different for exercising different muscles. For example the user may sit in an upright position to exercise his chest and have to lean forwards to exercise his shoulders with the same equipment.
Another limitation is that only approximately horizontal and vertical type pushing or pulling movements are allowed on current machines, However the muscles of the back are capable of pulling movements at any angle between horizontal, or below, and vertical and the muscles of the chest and shoulders can push at any angle between horizontal and vertical.